Electronic devices are found in all aspects of life. Of particular import are computers, which are found in homes and offices throughout the world. Computers are also being implemented more and more in machinery such as automobiles and aircraft. Further, it is now routine to ship computers and electronic components long distances, be it factory to retail outlet, factory to consumer, or warehouse to consumer.
One problem that continues to plague electronic devices is damage from physical shock. Physical shock can occur in many ways. During handling in a factory, retail store, or in a shipping warehouse, a component might be dropped. During transportation and for vehicle-mounted electronics, the vehicle carrying the electronic device might encounter potholes and other obstacles which jar the vehicle, translating the shock to the electronic device.
The problem caused by physical shock is even more pronounced in electronics having movable parts. For instance, hard disk drives (HDDs) have many moveable parts. A drop of four inches results in a shock of ˜300 G (300 times the force of gravity) to an HDD. Shock can damage these delicate parts of the drive, such as the pivot bearing of the actuator, the motor and spindle bearings, the head resting on the load/unload components, electric components, etc.
These parts are even more susceptible to physical shocks caused by rough handling, transportation, and use in hostile environments. Conventional usage of a HDD has been fairly gentle with respect to operating environments. HDDs in the past have been associated with usage that is constrained to withstand shock events that are generally very mild. However, HDDs are now being implemented in more hostile environments, including laptops and even in vehicles.
FIG. 1 is a cross-sectional diagram of parts of a data storage disk drive system (HDD) 30 including a rigid magnetic disk drive unit generally designated as 32 and a control unit generally designated as 34. Unit 32 is illustrated in simplified form sufficient for an understanding of the present invention because the utility of the present invention is not limited to the details of a particular drive unit construction. After data storage disk drive system 30 is completely assembled, servo information used to write and read data is written using the disk drive system 30.
Referring now to FIGS. 1 and 2 of the drawing, disk drive unit 32 includes a stack 36 of disks 38 having two magnetic surfaces 40. The disks 38 are mounted in parallel for simultaneous rotation on and by an integrated spindle and motor assembly 46. Data information on each disk 38 are read and/or written to by a corresponding transducer head 48 movable across the disk surface 40. In a disk drive using a dedicated or hybrid servo, one of the disk surfaces 40′ stores servo information used to locate information and data on the other disk surfaces 40.
Transducer heads 48 are mounted on flexure springs 50 carried by arms 52 ganged together for simultaneous pivotal movement about a support spindle 54. One of the arms 52 includes an extension 56 driven in a pivotal motion by a head drive motor 58. Although several drive arrangements are commonly used, the motor 58 can include a voice coil motor 60 cooperating with a magnet and core assembly (not seen) operatively controlled for moving the transducer heads 48 in synchronism in a radial direction in order to position the heads in registration with data information tracks or data cylinders 62 to be followed and access particular data sectors 64. Although a rotary actuator is shown, it should be understood that a disk drive with a linear actuator can be used. Data storage disk drive system 30 is a modular unit including a housing 66. The various components of the disk drive system 30 are controlled in operation by signals generated by control unit 34 such as motor control signals on line 46A and position control signals on line 58A.
As mentioned above, components of the HDD that are particularly susceptible to physical shock are the spindle bearing assemblies. FIG. 3 illustrates a detailed view of bearings 80 and races 82, 84. The bearings 80 rest against inner and outer races 82, 84. Because the bearings 80 are spherical, they only have one point of contact on each race 82, 84. The bearings 80 are much harder than the races 82, 84, so if a shock is inflicted, a bearing 80 will create a depression, or dent, in one or both races 82, 84. The race 82, 84 will scar and wear. Once a race 82, 84 has a scar, the drive will have a repeatable motion each time a bearing 80 contacts the scar. One result is a loud audible frequency noise. Another result is that the disk supported by the spindle will wiggle, resulting in operational instability.
Similar problems can also be found in other types of electronic devices, including CD and DVD players. Thus, the propensity for damage to electronics with moveable components presents a real problem.
Prior art attempts at reducing the damage inflicted by physical shock include surrounding the device in styrofoam or bubble wrap during shipping, and mounting sensitive components on rubber pads in the final device. However, these attempts provide only limited protection.
What is therefore needed is a new device that provides improved protection from physical shock.